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<p>TiO₂–rGO nanocomposite thin films were fabricated via spin coating at 4000&#xa0;rpm, with reduced graphene oxide (rGO) content systematically varied from 0.01 to 0.04 wt% to investigate its influence on structural, optical, and humidity-sensing properties. Controlled incorporation of rGO induced significant modifications in microstructure and surface morphology. At 0.04 wt%, a well-connected conductive network formed, in which TiO₂ nanoparticles were uniformly anchored onto multilayered rGO sheets, thereby facilitating efficient charge transport. Atomic force microscopy (AFM) revealed an average roughness (Sa) of 59.65&#xa0;nm and a root-mean-square roughness (Sq) of 75.37&#xa0;nm, indicating an increased surface area for adsorption, while the contact angle decreased to 12.1°, confirming improved hydrophilicity. XRD analysis revealed enhanced crystallinity with increasing rGO content, while optical studies indicated a gradual increase in optical bandgap from 2.60&#xa0;eV to 2.85&#xa0;eV with increasing rGO content, suggesting improved crystallinity and reduced defect-assisted localised states. Humidity-sensing measurements performed in the 30–85% RH range showed a reversible decrease in resistance with increasing humidity, with a sensitivity of 46.5 kΩ/%RH, response and recovery times of approximately 600&#xa0;s, good repeatability, and moderate hysteresis. The results demonstrate that controlled low-level rGO incorporation provides an effective approach for improving the functional performance of TiO₂-based humidity sensors using a simple precursor-free spin-coating method.</p>

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Influence of reduced graphene oxide on the structural, optical and humidity sensing performance of TiO₂ thin films

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Reshma Vasu,
  • T. Vasuki,
  • S. Ashokan

摘要

TiO₂–rGO nanocomposite thin films were fabricated via spin coating at 4000 rpm, with reduced graphene oxide (rGO) content systematically varied from 0.01 to 0.04 wt% to investigate its influence on structural, optical, and humidity-sensing properties. Controlled incorporation of rGO induced significant modifications in microstructure and surface morphology. At 0.04 wt%, a well-connected conductive network formed, in which TiO₂ nanoparticles were uniformly anchored onto multilayered rGO sheets, thereby facilitating efficient charge transport. Atomic force microscopy (AFM) revealed an average roughness (Sa) of 59.65 nm and a root-mean-square roughness (Sq) of 75.37 nm, indicating an increased surface area for adsorption, while the contact angle decreased to 12.1°, confirming improved hydrophilicity. XRD analysis revealed enhanced crystallinity with increasing rGO content, while optical studies indicated a gradual increase in optical bandgap from 2.60 eV to 2.85 eV with increasing rGO content, suggesting improved crystallinity and reduced defect-assisted localised states. Humidity-sensing measurements performed in the 30–85% RH range showed a reversible decrease in resistance with increasing humidity, with a sensitivity of 46.5 kΩ/%RH, response and recovery times of approximately 600 s, good repeatability, and moderate hysteresis. The results demonstrate that controlled low-level rGO incorporation provides an effective approach for improving the functional performance of TiO₂-based humidity sensors using a simple precursor-free spin-coating method.